Moss Plants and More: April 2013

May 2013 Desktop Calendar

I think that this moss covered rock looks a lot like a large turtle shell, or maybe a tortoise. It was about the size of the hood of a small car, so a lot larger than a turtle, but you get the idea.

This month's calendar was also taken at the top of the ridge in the Stebbins Cold Canyon Reserve. I wanted to be sure that I got the calendar prepped and posted before the start of the month. The las couple of months ran a little late.

1 - Single click on the image to open it up in a new window. (If you use the image directly from the blog post you will lose a lot of resolution.)

2 - Right-click (or ctrl-click) on the image, and chose the option that says, "Set as Desktop Background" or "Use as Desktop Picture". The wording may vary.

3 - If the image does not fit your desktop neatly, you may have to adjust the image (Mac: System Preferences - Desktop and Screen Saver - Desktop; Windows: Control Panel - Display - Desktop) and choose "Fill screen" as the display mode of your background image.

Mosses in the Arctic

When you think about the arctic what do you imagine? Things that come to mind for me are northern Canada, Siberia, flat, cold, caribou, reindeer, polar bears, and mosses. Yes, there are a lot of mosses that live in the arctic. Not many plants grow that far north, but mosses can handle the extremes. They are tough. There are not many different species of mosses in the arctic, but a significant bulk of the plant life (biomass) is mosses.

This study examines how much mosses contribute to the ecosystem by storing carbon in their plant bodies (biomass). They found that the mosses contributed 25% of the gross primary productivity (above and below ground growth) in the arctic ecosystem that they examined. This is a significant contribution to the ecosystem carbon cycle! Hence one of the authors' final conclusions is that mosses need to be included in vegetation carbon models in order to have an accurate picture of the carbon cycling.

I think that this is a really important take-home message. Especially in far northern ecosystems, mosses make up a large portion of the plant life. If we are to understand and plan for the effects of global climate change on these far northern places, we cannot ignore the mosses.

Street LE, Subke JA, Sommerkorn M, Sloan V, Ducrotoy H, Phoenix GK, Williams M (2013). The role of mosses in carbon uptake and partitioning in arctic vegetation. The New phytologist PMID: 23614757

Sphagnum mosses (aka. peat mosses, pictured below) were one of the focal species of their study.

Photosynthesis in Hornworts

Photosynthesis is the most important biological reaction on the planet. It creates the sugars and starches that we and other animals rely upon for food. Photosynthesis also helps to regulate the climate by binding up carbon from the air to keep the planet cooler. Plants need carbon dioxide, water, and light to carry out photosynthesis.

Hornworts have a cool structure called a pyrenoid that helps to increase the rate of photosynthesis in these plants. Pyrenoids increase the concentration of carbon dioxide close to the enzyme RuBisCO, which is critical for photosynthesis. A recent study examined pyrenoid evolution in the hornworts, the bryophyte lineage most closely related to flowering plants. They asked whether the evolution of the pyrenoid in hornworts was correlated with historically low levels of carbon dioxide in the atmosphere. It is predicted that low levels of carbon dioxide in the atmosphere would put pressure on plants to evolve mechanisms that enable them to increase the concentration of carbon dioxide in their cells in order to increase rates of photosynthesis.

Villarreal, J. & Renner, S. (2012). Hornwort pyrenoids, carbon-concentrating structures, evolved and were lost at least five times during the last 100 million years Proceedings of the National Academy of Sciences, 109 (46), 18873-18878 DOI: 10.1073/pnas.1213498109

Their results support the pyrenoid structure evolving 5 or 6 times across the hornworts (transition from blue to red in the figure below). Pyrenoid evolution does not appear to be synchronous, each time the pyrenoid evolved across the tree was at a different time in the past. If they had evolved in response to changes in the atmosphere, we would predict that they evolved at the same time. They also did not find a relationship between low atmospheric levels of carbon dioxide and pyrenoid evolution. Even when atmospheric carbon dioxide levels were low, new hornwort species evolved that did not have a pyrenoid. If the pyrenoid was really advantageous, we would predict that when the carbon dioxide levels were low only species with a pyrenoid would evolve new species. Based on this and other findings, they propose that the evolution of the pyrenoid may be related to something other than the atmospheric concentration of carbon dioxide

Figure 1 from Villarreal & Renner 2012. This shows the relationships
between different species of hornworts. The species in blue do not have pyrenoids
and the species in red do have pyrenoids. The black and white inset images show the
different types of pyrenoids found in hornwort species.

Who is your favorite scientist?

One of my favorite scientists is Dr. Katherine Esau. I think that her book Anatomy of Seed Plants is an invaluable resource for anyone interested in the structure of plants. It is just too bad that the text doesn't cover bryophytes and ferns. I would love to read her interpretations and thoughts for teaching students about bryophyte structures. We have tried using other textbooks to teach a university level plant anatomy course, such as Introduction to Plant Structure and Development, but ended up returning to Esau's text. The text is a little dated (the second edition came out in 1977), but only in the sense that it does not include the most recent literature and thus lacks a molecular perspective. (Books on plant structure and development that connect to gene function, which I like, include The Molecular Organography of Plants and Mechanisms in Plant Development.) Recently a 3rd edition of Esau's Anatomy of Seed Plants has been updated by Ray Evert. This version is a nice addition, but in my opinion is much more a reference book for your shelf than a text to be used for teaching. I think that Esau's Anatomy of Seed Plants is the best text to teach students the basics of interpreting plant structures.

Dr. Esau in 1958. Image from the collection of UC Santa Barbara,
Cheadle Center for Biodiversity and Ecological Restoration

Dr. Esau's early life was full of twists and turns. Her family fled Czarist Russia to Berlin in 1918/1919. Then she immigrated to the United States in 1922 and continued her studies out in California. A couple of nice articles have been written that summarize her life story. One is published in the Plant Science Bulletin and the other is in The Botanical Review.

Her research focused on the development and structure of plant phloem. Phloem are the cells that move sugars around inside the plant body. One of her major research tools was the electron microscope, pictured below. I think that electron microscopes are a lot of fun to use. It is amazing how far you can zoom in and all the cellular details that you can see!

Dr. Esau working at the microscope.
Image from the collection of UC Santa Barbara,
Cheadle Center for Biodiversity and Ecological Restoration

I was inspired to write this post by the blog Dead Scientist of the Week.

April 2013 Desktop Calendar

I went for a hike this weekend at the Stebbins Cold Canyon Reserve. It was a really great hike up into the Coast Range with some great views of the mountains and beyond! We saw some nice mosses like this small Fissidens and the spring wildflowers were in bloom.

1 - Single click on the image to open it up in a new window. (If you use the image directly from the blog post you will lose a lot of resolution.)

2 - Right-click (or ctrl-click) on the image, and chose the option that says, "Set as Desktop Background" or "Use as Desktop Picture". The wording may vary.

This is the view back into the mountains.

And this is looking over the ridge out into the central valley. We could see the towns of Winters and Davis, and then way off in the distance is the skyline of Sacramento.

I would definitely recommend this hike to anyone in the area. Great views from ~1500 feet up and a lot of great plants to check out!

Berry Go Round - March 2013

The newest edition of the plant carnival Berry Go Round is up at the blog In the Company of Plants and Rocks. There are some good plant posts in the line up that you should definitely check out.

The photos from Geotripper of spring wildflowers of the Sierra Nevada foothills are getting me excited about going hiking this upcoming weekend. We had a good amount of rain this week and I am looking forward to seeing some spring bryophytes in addition to the showy wildflowers.

I would also recommend checking out the post on bees, flowers, caffeine, and memory at SciLogs. I think it is a really interesting study and those of you who love coffee and the effects of caffeine will find this study quite interesting.

Those are just a couple of highlights from the carnival. Head to In the Company of Plants and Rocks for the full carnival experience. For more about blog carnivals and my posts about the earlier editions of Berry Go Round, click here.